Trailer for mower

ABSTRACT

The present invention is directed to a trailer for a lawn mower and more particularly to a system and method of charging a variety of batteries of the lawn mower including connecting the lawn mower to a towing vehicle, either directly or by placing the lawn mower on a trailer, towing the lawn mower, generating electricity upon towing the lawn mower utilizing a generator mechanically coupled to the wheels of the trailer. The generator converts the mechanical energy into electrical energy. The generator is electrically coupled to first type of battery and a second type of battery that is connected to the lawn mower and/or a first type of battery and a second type of battery that is connected to a charging station on the trailer. The system also includes a charging circuit for each of the first type of battery and the second type of battery.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/049,979, filed on Feb. 22, 2016, which claims priority toU.S. Provisional Application 62/118,643, filed on Feb. 20, 2015. Thedisclosure of the above application is incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to power tool cordless systems.

BACKGROUND

Lawn mowers used by landscaping providers are typically moved fromlocation to location by placing the mower on a trailer and pulling thetrailer by a driven vehicle, such as a pickup truck. Furthermore, mowersare typically powered by internal combustion engines to drive the mowerwheels and the cutting blades. These mowers may also include an internalbattery for powering electrical elements of the mower. Alternate mowersmay include an electric motor and a battery for powering the electricmotor wherein the electric motor drives the mower wheels and the cuttingblades.

Additionally, landscaping providers utilize cordless, battery operatedpower tool to provide various services including, for example, suchtools as string trimmers, blowers, and drills.

It would be desirable to provide a system and method for charging themower batteries and/or the cordless power tool batteries duringtransportation of the mower from location to location.

SUMMARY

In one general aspect, the present invention may include a lawn mower,comprising at least two wheels for driving the mower; at least one bladefor cutting grass; a generator for generating electricity; an electricmotor electrically coupled to the generator for receiving the generatedelectricity, the electric motor coupled to the at least two wheels fordriving the at least two wheels and/or the at least one blade fordriving the at least one blade; a charging circuit electrically coupledto the generator for receiving the generated electricity; and at leastone receptacle for receiving a removable battery pack, the receptacleincluding an electrical interface for electrically coupling thereceptacle to the charging circuit to provide a charging current fromthe charging circuit to the receptacle and a mechanical interface forreceiving and physically coupling the battery pack to the receptacle,wherein the electrical interface and the mechanical interface aresubstantially similar to an electrical interface and a mechanicalinterface of a cordless power tool such that the battery pack mayelectrically and mechanically couple to the mower electrical andmechanical interfaces to receive a charging current from the chargingcircuit and to the power tool electrical and mechanical interface toprovide a discharging current to the power tool to operate the powertool.

In another aspect, the present invention may include a lawn mowercomprising at least two wheels for driving the mower; at least one bladefor cutting grass; a generator mechanically coupled to at least one ofthe at least two wheels, wherein the generator converts mechanicalenergy generated by the at least one of the at least two wheels intoelectrical energy as the at least two wheels rotate when the mower isbeing pulled on a road; a first charging circuit electrically coupled(a) to the generator for receiving electricity and (b) to the firstbattery for providing a charging current to the first battery; a secondbattery; and a second charging circuit electrically coupled (a) to thegenerator for receiving electricity and (b) to the second battery forproviding a charging current to the second battery.

In another aspect, the present invention may include a trailer fortransporting a lawn mower, comprising a platform for supporting themower; at least two wheels for supporting the platform on a road; agenerator mechanically coupled to at least one of the at least twowheels, wherein the generator converts mechanical energy generated bythe at least one of the at least two wheels into electrical energy asthe at least two wheels rotate when the trailer is being pulled on theroad; an electrical cable coupled at a first end to the generator forproviding electricity; and a coupler connected to a second end of theelectrical cable for electrically coupling to a mating coupler of themower for providing electricity to the mower.

In another aspect, the present invention may include a lawn mower,comprising at least two wheels for driving the mower; at least one bladefor cutting grass; an electric motor electrically coupled to the atleast two wheels for driving the at least two wheels and/or the at leastone blade for driving the at least one blade when the motor is turningin a first direction and for generating electricity when the motor isturning in a second direction opposite the first direction; a chargingcircuit electrically coupled to the electric motor for receiving thegenerated electricity; at least one receptacle for receiving a removablebattery pack, the receptacle including an electrical interface forelectrically coupling the receptacle to the charging circuit to providea charging current from the charging circuit to the receptacle and amechanical interface for receiving and physically coupling the batterypack to the receptacle, wherein the electrical interface and themechanical interface are substantially similar to an electricalinterface and a mechanical interface of a cordless power tool such thatthe battery pack may electrically and mechanically couple to the mowerelectrical and mechanical interfaces to receive a charging current fromthe charging circuit and to the power tool electrical and mechanicalinterface to provide a discharging current to the power tool to operatethe power tool.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate preferred embodiments of theinvention according to the practical application of the principlesthereof, and in which:

FIG. 1 illustrates a cordless system according to a first aspect of theinvention;

FIG. 2 is a partial rear view of a mower of the cordless system of FIG.1;

FIG. 3 is a block diagram showing an exemplary drive apparatus for themower of FIGS. 1-2;

FIG. 4 illustrates a first exemplary embodiment of a mower and acharging system for charging batteries of the cordless system of FIGS.1-2;

FIG. 5 illustrates a second exemplary embodiment of a mower and acharging system for charging batteries of the cordless system of FIGS.1-2;

FIG. 6 is a block diagram of an exemplary charging system including acharging station of FIG. 5;

FIG. 7 illustrates a third exemplary embodiment of a mower and acharging system for charging batteries of the cordless system of FIGS.1-2;

FIG. 8 is an exploded view of an exemplary hub motor used in a trailerof FIG. 7;

FIG. 9 illustrates a fourth exemplary embodiment of a mower and acharging system for charging batteries of the cordless system of FIGS.1-2;

FIGS. 10-11 illustrate a fifth exemplary embodiment of a mower and acharging system for charging batteries of the cordless system of FIGS.1-2 where

FIG. 10 shows the mower in a first position and FIG. 11 shows the mowerin a second position.

DETAILED DESCRIPTION

The invention is now described with reference to the accompanyingfigures, wherein like numerals designate like parts. FIGS. 1-2 show amower 100, which is preferably a riding mower. The mower 100 can be anelectric mower which is driven by an electric motor, a gas mower whichis driven by a gas engine, or a hybrid mower which has both an electricmotor and a gas engine.

One drive apparatus for such a hybrid mower 100 is described in U.S.Pat. No. 5,323,868, which is hereby incorporated by reference. Such adrive apparatus is shown in FIG. 3. The hybrid mower 100 may have a gasengine 101 to be driven by fuel such as gasoline, a generator 102 drivenby the engine 101 for generating DC electricity, a battery 103 foraccumulating and storing the electricity generated by the generator 102,an inverter/rectifier 104 for converting DC electricity from thegenerator 102 and the battery 103 into AC electricity, an inductionmotor 106 to be driven by the AC electricity, and a transmission orgearbox 107 for transmitting the driving force of the motor 106 to a setof tires 108.

With such a drive apparatus, fuel such as gasoline is supplied to theengine 101 for rotation (at a predetermined RPM). The torque of theengine 101 is preferably transmitted to the generator 102 for conversioninto DC electricity. Of the thus generated electricity, an amountsufficient to drive the motor 106 is preferably sent to the motor 106via the inverter 104. The surplus DC electricity is preferablyaccumulated in the battery 103 which is capable of accepting relativelyhigh charging currents and being charged at high charging rates.

The torque of the motor 106 is transmitted to the tires 108 via thetransmission 107 to cause the hybrid mower 100 to travel. When theelectricity sent to the motor 106 from the generator 102 is not enoughto drive the motor 106, the battery 103 provides supplemental power tothe inverter 104 and thus to the motor 106. The supply of electricity tothe motor 106 is varied by controlling a built-in switching device ofthe inverter 104 to react accordingly to the extent of stepping on theaccelerator or gas pedal.

To lower the speed of the hybrid mower 100, regenerative braking is usedas a counterpart to engine braking. Regenerative braking is performed asthe switching device built into the inverter 104 is controlled. Duringthis regeneration, rotational energy is given to the motor 106 from thetires 108 via the transmission 107. Regenerated electricity is producedfrom the motor 106. The regenerated electricity is converted into DCelectricity by the inverter 104, and is then accumulated in the battery103.

Persons skilled in the art will recognize that, if DC motors are usedinstead of the induction motor 106, the entire electrical system of thehybrid mower 100 could be DC-based and thus obviating the need forinverter 104.

A second electric induction motor 109 is preferably connected toinverter 104. The torque of the motor 109 is transmitted to a set ofcutting blades 111 via a transmission 110 to cause the hybrid mower 100to cut grass or vegetation.

Also connected to the inverter 104 is a low charging rate chargingcircuit 105, which can provide charging current to charge one or morepower tool battery packs 115, which are capable of accepting relativelylow charging currents and being charged at relatively low chargingrates. It should be understood that the terms “low” and “high” aresimply intended to be relative terms. As such, a low charging ratecharging circuit simply provides a charging current and a charging rateless than a high charging rate charging circuit and a high charging ratecharging circuit provides a charging current and a charging rate greaterthan a low charging rate charging circuit. Such power tool battery packs115 are described in US Patent Publication No. 2014/0272516, filed onMar. 15, 2013, and U.S. Patent Application No. 62/000,112, filed May 18,2014, which are hereby fully incorporated by reference. The power toolbattery packs 115 can be connected to (1) a separate charger 120 forcharging, (2) a power tool, such as drill 122, and/or (3) an outdoorpower tool, such as a hedge trimmer or chain saw 124, for cuttingvegetation, as shown in FIG. 1. The charging circuit 105 may alsocontrol as display 126, as shown in FIGS. 2-3, in order to indicate tothe user which of the power tool battery packs 115 have been fullycharged and/or the state of charge of the power tool battery packs 115.

Persons skilled in the art will recognize that the high charging ratecharging circuit may provide high charging currents and current rates tothe battery 103 resulting in relatively high power transfers (at least500 watts and preferably at 3.5 kilowatts) to the battery 103. Dependingon the characteristics of the battery 103, the battery 103 could beprovided with power transfers on the order of about 10 kilowatts andpreferably 25 kilowatts. However the low charging rate charging circuit105 may only provide power transfers below 500 watts, even if thenominal voltage of the power tool battery pack 115 (between about 14volts and about 60 volts) is different than the nominal voltage of thebattery 103 (between around about 12 volts and about 48 volts).

Persons skilled in the art will recognize that the type of chargingcircuit 105 that is connected to inverter 104 is one that can preferablyconvert AC power into DC charging currents. However, charging circuit105 can be connected to battery 103, in which case the charging circuit105 can control the amount of DC charging current sent to the differentbattery packs 115. The charging circuit 105 may charge the power toolbattery packs 115 according to the algorithms and sequences taught in USPatent Publication No. 2013/0335014, filed on Feb. 18, 2013, which ishereby fully incorporated by reference.

Persons skilled in the art will recognize that, in an electric mower100, the charging circuit 105 could similarly be connected to anon-board mower battery or an inverter connected to the mower battery103. Similarly, in a gas mower 100, the charging circuit 105 couldsimilarly be connected to an on-board mower battery 103 or to aninverter/rectifier 104 connected to the mower battery 103 or to agenerator 102 driven by the mower's gas engine 101.

Persons skilled in the art will recognize that providing a low chargingrate charger circuit 105 will facilitate access to the charged powertool battery packs 115, as the user would not have to walk over to acharger 120. Instead a person driving the mower 100 can just drive themower 100 to a location where the charged power tool battery packs 115are needed.

It may be advantageous to maximize charging time for the power toolbattery packs 115 and/or the battery 103. Accordingly, FIGS. 4-10illustrate different systems that may implement various methods forcharging such batteries during transportation of the mower 100.

Referring to FIG. 4, a first exemplary embodiment of a mower and acharging system for charging batteries of the cordless system isillustrated. Therein, a trailer 200 is attached to a vehicle 300. Thetrailer 200 may carry the front wheels 128 of the mower 100, allowingthe rear wheels 108 to rotate as the vehicle 300 travels to the nextdestination. As the wheels 108 rotate, rotational energy is provided tothe motor 106 from the wheels 108 via the transmission 107. Regeneratedelectricity is produced from the motor 106. This regenerated electricityis converted into DC electricity by the rectifier 104, and is thenaccumulated in the battery 103. The regenerated electricity can also beused to power the charging circuit 105 and thus charge the power toolbattery packs 115.

Preferably the trailer 200 is a powered trailer electrically connectedto the battery of the vehicle 300. The trailer 200 may have a frontfixed portion 202 attached to a towing hitch 201 of the vehicle 300, anda rear movable portion 204 pivotally attached to the front fixed portion202. A motor 206 may cause the rear movable portion 204 to pivotrelative to the front fixed portion 202. A user may control the rotationof the rear movable portion 204 via control buttons 208. The rearmovable portion 204 may have a flap 210 pivotally attached thereto, inorder to facilitate loading the mower 100 onto the trailer 200.

Referring to FIGS. 5-6, a second exemplary embodiment of a mower and acharging system for charging batteries of the cordless system isillustrated. Therein, a trailer 250 is attached to the vehicle 300 via astandard towing hitch 201. The trailer 250 has a set of wheels 251connected to a generator or an alternator 252 via a belt or chain 253.Accordingly, as the trailer 250 is pulled by the vehicle 300, at leastone of the wheels 251 and the generator/alternator 252 generateelectricity.

The mower 100 may be connected to the generator/alternator 252 via acable 255. The generated electricity can be used to charge the powertool battery packs 115 and/or the battery 103. As shown in FIG. 5, thecable 255 may be connected to the mower 100 at a point D (see FIG. 3),which in turn is connected to a high charging rate charging circuit 113for charging the battery 103. Persons skilled in the art will recognizethat the charging circuit 1113 may be disposed within the mower 100, oroutside of the mower 100. For example, the charging circuit 113 could beintegrated with the cable 255 or the generator/alternator 252.

The trailer 250 may have a charging station 254 with a charging circuit256 connected to the generator/alternator 252 via an electricalconnection 257. The generator/alternator 252 generates high currents andis capable of providing power for the high charging rate chargingcircuits. The charging circuit 256 receives the high current electricitygenerated by the generator/alternator 252 and provides charging currentsto the power tool battery packs 115 via the charging circuit 105.

The charging station 254 may also charge a supplemental battery 103 thatis separate from the mower 100. In this manner, if the battery 103 inthe mower 100 is discharged beyond the allowed parameters, the user canquickly swap the discharged battery 103 with a charged battery 103.Referring to FIG. 6, the generator/alternator 252 can power a highcharging rate charging circuit 113 for charging the supplemental battery103. The generator/alternator 252 may also power a low charging ratecharging circuit 105 for charging the power tool battery packs 115. Thecharging circuit 105 may also be powered by the supplemental battery103. A relay switch 258 can be used to select the power source for thecharging circuit 105, where the relay switch 258 selects thesupplemental battery 103 as the power source when the supplementalbattery 103 is connected to the charging circuit 113. This embodimenttakes full advantage of the high currents generated by the generator 252by charging the high charge current battery 103 in the mower with highcharging currents by the high charging rate charging circuit 113 in themower (relatively quickly) and/or by charging the alternate high chargecurrent battery 103 in the charging station 254 with high chargingcurrents by the high charging rate charging circuit 113 in the chargingstation 254 (relatively quickly) and/or by charging the low chargecurrent battery 115 in the mower 100 with low charging currents by thelow charging rate charging circuit 105 in the mower 100 (relativelyslowly) and/or by charging the low charge current battery 115 in thecharging station 254 with low charging currents by the low charging ratecharging circuit 105 in the charging station 254 (relatively slowly).Additionally, the batteries 103 (either in the mower 100 or the chargingstation 254) can charge the batteries 115 (in the mower 100 or thecharging station 254, respectively) with low charging currents by thelow charging rate charging circuit 105 (in the mower 100 or the chargingstation 254, respectively) when power is not being generated by thegenerator 252, i.e., when the trailer 300 is not moving. In this manner,in one situation, the high charge current batteries 103 (in the mower100 and the charging station 254) can be charged quickly with highcharging currents when the trailer 300 is moving and the high currentsare available (taking full advantage of the available high chargingcurrents) and then the high charge current batteries 103 can charge thelow charge current batteries 115 at the low charging currents when thehigh charging currents are not available.

A pivotable gate 260 may be connected to trailer 250. A flange 262 maybe disposed on a platform 263 of the trailer 250. The flange 262 mayhave a curved slot 264. A handle 266 extends through slot 264 andthreadingly engages the gate 260. With such construction, the user canrotate the gate 260 and lock it at a particular pivotal position byrotating handle 266.

FIGS. 7-8 illustrate a third exemplary system for charging batteriesand/or battery packs, where like numerals refer to like parts. Insteadof having a separate generator/alternator 252, this embodiment includesa wheel hub motor 270 cooperating with the wheel 251. An exemplary hubmotor can be found disclosed in US Publication No. 2014/0374178, filedDec. 26, 2013, which is hereby fully incorporated by reference.

As shown in FIG. 8, the hub motor 270 has a stator 272 containingelectric magnets and electronics for controlling the generated magneticfields, and a rotor 274 slipped over the stator 272. The wheel 251 isbolted onto the rotor 274 via a set of bolts 276. Rather than using thehub motor 270 for driving the wheel 251, the hub motor 270 is usedherein for power generation. Accordingly, as the trailer 250 is pulledby the vehicle 300, the wheel 251 rotates, causing the rotor 274 torotate around the stator 272. Because the rotor 274 preferably has a setof permanent magnets, the magnetic field of such magnets induces acurrent in a set of coils surrounding the electric magnets in the stator272.

This generated current can be conducted via the cable 255 to the highcharging rate charging circuit 113 for charging the high charge currentbattery 103. Persons skilled in the art will recognize that, asdescribed above, the high charge current battery 103 can be used topower the low charging rate charging circuit 105 to charge power toolbattery packs 115.

FIG. 9 illustrates another alternate exemplary trailer 250, where likenumerals refer to like parts. Instead of having a generator/alternator252 driven by the wheel 251, the trailer 250 preferably has a separategenerator assembly 280, which has a wheel 282, a generator/alternator284, and a transmission 286 connecting the generator wheel 282 and thegenerator/alternator 280 so that rotation of the generator wheel 282causes the generator/alternator 280 to generate electrical power.

This generated current can be conducted via the cable 255 to the highcharging rate charging circuit 113 for charging the high charge currentbattery 103. Persons skilled in the art will recognize that, asdescribed above, the battery 103 can be used to power the low chargingrate charging circuit 105 to charge the power tool battery packs 115 orthe current can be provided directly to the charging circuit 105 fromthe generator/alternator 280 via the cable 255 and a switch 258.

Persons skilled in the art will recognize that the generator assembly280 can be separate from the trailer 250 and that it preferably can beremoved and installed on different trailers, as necessary or desired.

Referring to FIGS. 1 and 10-11, the mower 100 may have a pivotable hitch140 for engaging a ball hitch 302 of the vehicle 300. The hitch 140 maybe moved between a storage position (shown in broken lines in FIG. 1)and an extended position (shown in solid lines in FIG. 1) for engagingthe ball hitch 302.

Persons skilled in the art will recognize that it is desirable to lockthe hitch 140 in the extended position and/or the storage position. Apin (not shown) can be used to lock the hitch 140 in the desiredposition.

The hitch 140 may have a cam surface 142 which can contact and ride on acam surface 304 of ball hitch 302. Accordingly, the user can drive themower 100 towards the vehicle 300. The hitch 140 will contact and rideon the cam surface 304, lifting the hitch 140. As the mower 100 movesfurther towards the vehicle 300, the hitch 140 will move above and thenfall on a ball post 306, thereby hitching the mower 100 to the vehicle300. The battery 103 can be then be charged as described above while thevehicle 300 tows the mower 100, causing the wheels 108 to rotate.

Persons skilled in the art will recognize that some mowers 100 may havetransmissions 107 that do not easily allow for rotation of the wheels108 at high speed. Accordingly, the mower 100 may be provided with atleast one generator wheel assembly 290. The generator wheel assembly 290preferably has an arm 292 pivotally connected to the mower 100, and awheel 294 preferably disposed at a distal end of the arm 292. The wheel294 is operatively connected to a generator/alternator (not shown) in asimilar manner as described above so that, when the wheel 294 rotates,the generator/alternator produces charging currents that can charge thebattery 103 and/or the power tool battery packs 115.

Preferably the arm 292 is connected to a motor 296 which can rotate thearm 292 (and thus wheel 294) downwardly towards the ground. The motor296 preferably has sufficient torque to lift up the mower 100, so thatthe wheels 108 are not contacting the ground. Instead the mower 100 issupported above the ground by the ball hitch 302 and the wheel(s) 294.

Alternatively, the arm 292 may be disposed in the lower position (notcontacting the ground). The arm 292 may be fixedly attached to the mower100 (thus obviating the need for the motor 296). Instead of driving themower 100 into the ball hitch 302, the user would move the hitch 140onto the ball hitch 302, then lift and push the mower 100. In thismanner, the hitch 140 can engage the ball hitch 302, and the wheels 108are lifted so that they are not contacting the ground. Instead the mower100 is supported above the ground by the ball hitch 302 and the wheel(s)294.

Persons skilled in the art may recognize other additions or alternativesto the means disclosed herein. However, all these additions and/oralterations are considered to be equivalents of the present invention.

1. A trailer for transporting a lawn mower, comprising: a platform forsupporting the mower; at least two wheels for supporting the platform ona road; a generator mechanically coupled to at least one of the at leasttwo wheels, wherein the generator converts mechanical energy generatedby the at least one of the at least two wheels into electrical energy asthe at least two wheels rotate when the trailer is being pulled on theroad; an electrical cable coupled at a first end to the generator forproviding electricity; and a coupler connected to a second end of theelectrical cable for electrically coupling to a mating coupler of themower for providing electricity to the mower.
 2. The trailer, as recitedin claim 1, further comprising a charging station, a second electricalcable coupled at a first end to the generator for providing electricityand at a second end to the charging station for providing electricityfrom the generator to the charging station.
 3. The trailer, as recitedin claim 1, wherein the charging station further comprises a firstcharging circuit and a second charging circuit, wherein the firstreceptacle is coupled to the first charging circuit and the secondreceptacle is coupled to the second charging circuit
 4. The trailer, asrecited in claim 3, wherein the first charging circuit provides a firstcharging current and the second charging circuit provides a secondcharging current wherein the first charging current is greater than thesecond charging current.
 5. The trailer, as recited in claim 3, furthercomprising a switch having a first input electrically coupled to thesecond end of the second electrical cable for receiving electricity fromthe generator and a second input electrically coupled to the firstreceptacle for receiving electricity from the first receptacle and anoutput selectively connectable to the first input and the second inputfor providing electricity to the second charging circuit.
 6. Thetrailer, as recited in claim 1, wherein the generator is part of one ofthe at least two wheels.